The long-term objective of this research is to understand the mechanisms whereby hormonal and local factors control the structure-function of the follicle and corpus luteum, and hence fertility, in primates during the menstrual cycle. Growing evidence indicates that vital actions of the primary luteotropic hormone in women and nonhuman primates, i.e., luteinizing hormone (LH), are mediated by the local effects of the progesterone (P)-receptor (PR) system in the ovulatory follicle and corpus luteum. During the past grant interval, research in rodents and monkeys identified events (e.g., tissue remodeling, protease expression) that may be regulated by specific PR isoforms, as well as novel local systems that may mediate LH and/or P actions in the ovary. Therefore, further studies are proposed to test the hypotheses that changes in: (Aim No. 1) genomic PR-A/-B isoforms; (Aim No. 2) members of protease families (e.g., matrix metalloproteases, MMPs; a disintegrin and metalloprotease with thrombospondin motifs, ADAMTS; serine proteases, cysteine proteases) plus their endogenous inhibitors, and (Aim No. 3) the corticotropin-releasing hormone-receptor- binding protein (CRH-R-BP) system, are gonadotropin- and steroid/P-regulated and critical for ovulation or luteinization of the follicle and development or maintenance of the corpus luteum. Two treatment protocols using adult, female rhesus monkeys will be employed, in which luteotropic support is "clamped" to rule out steroid effects via the hypothalamic-pituitary axis, either during the periovulatory interval (Protocol 1: GnRH antagonist plus an hCG bolus) or the luteal phase (Protocol 2: GnRH antagonist plus hl_Htid) of the natural menstrual cycle. Protocols are combined with steroid ablation (using a 3p-hydroxysteroid dehydrogenase inhibitor) and P (R5020) or other steroid (estrogen, R2858 or androgen, dihydrotestosterone) replacements. PRs, proteases and CRH-R-BP family members will be analyzed for mRNA expression (cDNA superarrays; real-time PCR) and localization (in situ hybridization), plus protein levels (Western blotting, ELISAs) and localization (immunocytochemistry). Protease activity will be analyzed by substrate assays. The role of PR isoforms, proteases and the CRH-R-BP system will be tested by local (e.g., intrafollicular or luteal) administration of specific agonists (e.g., PR-A agonist) or inhibitors (e.g., the MMP inhibitor, TAPI-0; the CRH antagonist, Astressin B). These studies will provide novel insight into gonadotropin-stimulated and steroid/P- dependent versus -independent processes in the ovulatory, luteinizing follicle and corpus luteum in primates. This work should also aid in understanding the etiology and treatment of certain types of infertility (e.g., luteinized unruptured follicles and luteal phase defects) and suggest novel contraceptive approaches for women.